A IR detector array typically comprises a number of rows and columns of detector elements. In a pyroelectric detector array for example, each column of elements of the array is connected to a column amplifier via a common sense line. In such a scheme there is one column amplifier per column of detector elements. In a pyroelectric detector array each element in each row is turned on, and by means of multiplexing (addressing) switches each row element is connected to its corresponding common sense line on a row by row basis.
Such an architecture and addressing approach is commonly used in a resistive bolometer array application. An example is disclosed by B. E. Cole, R. E. Higashi and R. A. Wood, in xe2x80x9cMonolithic Two Dimensional Arrays of Micromachined Microstructures for Infrared Applicationsxe2x80x9d Proc. IEEE, 86, 1679-1686, 1998. In this application however, if each element in a row is turned on, a large power consumption may result and this may cause the detector array to operate incorrectly. To reduce the power consumption to a practical limit and so maintain good IR detection performance only a small number of elements may be turned on in each row in turn. In this situation the bolometer array will output signals only onto a small number of column sense lines at any one time. By suitable addressing, the elements in each row which are turned on are moved in a pulsed fashion across the row in such a way that only a constant number of elements is on at any one time. Because only a small number of bolometer elements and hence column sense lines are active at any one time, the column amplifiers connected to the column sense lines that are not active are redundant and consume unnecessary power. It would therefore be advantageous to use fewer column amplifiers.
In one aspect, the present invention provides a two dimensional array of resistive bolometers arranged in rows and columns having a plurality of amplifiers for amplifying signals obtained from the bolometers wherein the number of amplifiers is less than the number of columns and the elements of a column are connected to a column sense line and a plurality of column sense lines are connected to each amplifier via a respective multiplexer for each amplifier.
In another aspect, the present invention provides a two dimensional array of resistive bolometers arranged in rows and columns having a plurality of amplifiers for amplifying signals obtained from the bolometers wherein the number of amplifiers is less than the number of columns, the elements of a column are connected to a column sense line, a plurality of column sense lines are connected to each amplifier with an equal number for each amplifier, such that if the columns are numbered consecutively according to their physical locations, the difference between successive column numbers for columns connected to the same amplifier equals the number of amplifiers, characterised in that the column sense lines are connected to each amplifier via a respective multiplexer for each amplifier, and the multiplexers are arranged to connect to the amplifiers sequential groups of adjacent column sense lines such that after each row element in the array is addressed and read out, the multiplexer connected to the column for that row element increments to the next unconnected column sense line.